Conventionally, gas barrier films in which a metal oxide thin film of aluminum oxide, magnesium oxide, silicon oxide, silicon nitride, silicon oxynitride, or the like is formed on the surface of a plastic film have been widely employed in the packaging of products requiring the blocking of various gases such as water vapor and oxygen, and in packaging applications to prevent the deterioration of foods, industrial products, pharmaceuticals, and the like.
In recent years, the use of plastic film substrates instead of glass substrates, which are heavy and tend to crack, has begun. Plastic film substrates are suited to roll to roll methods, making them advantageous in terms of cost. However, plastic film substrates present a problem in the form of water vapor barrier properties that are inferior to those of glass substrates. Thus, when plastic film substrates are employed in liquid crystal display elements, water vapor penetrates into the liquid crystal cells, causing display defects.
For use in actual display elements, the formation of a layer having antireflective properties is indispensable to increasing visibility. Conventionally, a laminate film of a high refractive index layer and a low refractive index layer has been proposed as an antireflective film for display elements. These laminate films are usually formed by the sputtering method or the reactive sputtering method (for example, Patent Reference 1). Additionally, display elements and liquid crystal display elements deteriorate rapidly in the presence of oxygen and water vapor. Thus, display elements need to be protected with a layer having gas barrier properties. Accordingly, there is a strong need for the development of a film possessing both gas barrier properties and antireflective performance. The use of a gas barrier film in which a laminate of the organic/inorganic lamination type is formed on a plastic film is known to solve this problem. Patent Reference 2 discloses a gas barrier film in which an organic layer of a cured composition containing a hexafunctional acrylate or methacrylate monomer or oligomer, and an inorganic layer comprised of an oxide selected from among aluminum oxide, silicon oxide, and a complex oxide of indium and tin are laminated. Although Patent Reference 2 states that the barrier property increases with the quantity of hexagonal acrylate monomer or the like in the composition to be cured in a range of 30 weight % and above, a content of 100 weight % only keeps the water vapor permeability to 0.08 g/m2/day. Additionally, further better barrier properties are demanded of substrates used in organic EL elements. The water vapor permeability is preferably less than 0.005 g/m2/day, which is the detection threshold by the MOCON method.
To solve this problem, Patent Reference 3 discloses the technique of achieving a water vapor permeability of less than 0.005 g/m2/day by employing a barrier layer in the form of an alternating laminate of multiple layers of organic layers and inorganic barrier layers. According to the Description, the water vapor permeability is 0.011 g/m2/day, confirming the technical value of multilayer laminates.